The following abbreviations and acronyms are herewith defined, at least some of which are referred to within the following description.
Third Generation Partnership Project (“3GPP”), Access and Mobility Management Function (“AMF”), Carrier Aggregation (“CA”), Clear Channel Assessment (“CCA”), Control Channel Element (“CCE”), Channel State Information (“CSI”), Common Search Space (“CSS”), Downlink Control Information (“DCI”), Downlink (“DL”), Enhanced Clear Channel Assessment (“eCCA”), Enhanced Mobile Broadband (“eMBB”), Evolved Node B (“eNB”), European Telecommunications Standards Institute (“ETSI”), Frame Based Equipment (“FBE”), Frequency Division Duplex (“FDD”), Frequency Division Multiple Access (“FDMA”), Frequency Resource Unit (“FRU”), Guard Period (“GP”), Hybrid Automatic Repeat Request (“HARQ”), Internet-of-Things (“IoT”), Key Performance Indicators (“KPI”), Licensed Assisted Access (“LAA”), Load Based Equipment (“LBE”), Listen-Before-Talk (“LBT”), Long Term Evolution (“LTE”), LTA Advanced (“LTE-A”), Medium Access Control (“MAC”), Multiple Access (“MA”), Modulation Coding Scheme (“MCS”), Machine Type Communication (“MTC”), Massive MTC (“mMTC”), Multiple Input Multiple Output (“MIMO”), Multipath TCP (“MPTCP”), Multi User Shared Access (“MUSA”), Narrowband (“NB”), Network Function (“NF”), Next Generation Node B (“gNB”), Policy Control & Charging (“PCC”), Policy Control Function (“PCF”), Quality of Service (“QoS”), Quadrature Phase Shift Keying (“QPSK”), Resource Block (“RB”), Radio Resource Control (“RRC”), Receive (“RX”), Switching/Splitting Function (“SSF”), Scheduling Request (“SR”), Session Management Function (“SMF”), System Information Block (“SIB”), Transport Block (“TB”), Transport Block Size (“TBS”), Transmission Control Protocol (“TCP”), Time-Division Duplex (“TDD”), Time Division Multiplex (“TDM”), Time Resource Unit (“TRU”), Transmission and Reception Point (“TRP”), Transmit (“TX”), Uplink Control Information (“UCI”), User Datagram Protocol (“UDP”), User Entity/Equipment (Mobile Terminal) (“UE”), Uplink (“UL”), Physical Downlink Control Channel (“PDCCH”), Physical Downlink Shared Channel (“PDSCH”), Physical Uplink Control Channel (“PUCCH”), Physical Uplink Shared Channel (“PUSCH”), Physical Resource Block (“PRB”), Universal Mobile Telecommunications System (“UMTS”), Ultra-reliability and Low-latency Communications (“URLLC”), and Worldwide Interoperability for Microwave Access (“WiMAX”).
In an LTE mobile communication network, a user equipment (“UE”) transmits uplink control messages on a physical uplink control channel (“PUCCH”). The PUCCH carries uplink control information (“UCI”) such as HARQ-ACK feedback, scheduling request (“SR”), and channel state information (“CSI”), and generally spans the entire subframe duration (i.e. 1 millisecond or 14 OFDM symbol durations).
The long transmission time of LTE PUCCH is not suitable to achieve HARQ round trip time (RTT) as short as 1 slot period in fifth generation radio access (e.g., 1 ms or 0.5 ms). Moreover, for low-latency communication, DL-to-UL switching may occur in every slot (e.g., 7 or 14 OFDM symbols). Thus, a guard period (“GP”) based on the maximum expected propagation delay in a cell would lead a very high GP overhead. Considering that the minimum GP in LTE TDD is one OFDM symbol period, the minimum GP overhead with 1 ms switching cycle is 14% or 7%, i.e. 1 symbol GP out of every 7 or 14 symbols.